Noun

1. A junction of highways on different levels that permits traffic to move from one to another without crossing traffic streams
2. Mutual interaction; the activity of reciprocating or exchanging (especially information)
3. The act of changing one thing for another thing
4. Reciprocal transfer of equivalent sums of money (especially the currencies of different countries)

Verb

1. Put in the place of another; switch seemingly equivalent items
2. Give to, and receive from, one another
3. Cause to change places
4. Reverse (a direction, attitude, or course of action)